Slab-to-Column Seismic Pounding Between Multistorey Buildings: Influence of the Impact Point Location and the Pre-Existing Gap Size

The present paper deals with the asymmetric seismic interaction phenomenon between multistorey reinforced concrete buildings. The paper focuses on the so-called floor-to-column pounding and aims to identify the influence of two specific factors: the exact impact point location and the width of the pre-existing separation gap between the interacting structures. Furthermore, the estimation of the effective impact length, i.e., the part of the external columns directly suffering the hit within their clear height that experiences severe damage, is attempted. For this purpose, several interaction cases are analyzed by means of inelastic dynamic analysis, and representative response quantities are calculated. In addition, a well-documented analytical procedure is applied in order to determine the effective impact length. The whole investigation highlights the crucial role of the impact point location for the local response of the external columns. On the contrary, it demonstrates that the overall building behavior is not considerably affected. In addition, it reveals that the existence of inadequate seismic joints may be more unfavorable in comparison with the complete absence of separation between the interacting structures. Thus, the relevant code provisions imposing a minimum seismic joint width should be strictly abided by. Finally, the investigation confirms field observations and experimental results which indicate that the damage of external columns which undergo strong pounding forces is limited to a short area with length equal to about 1 m or less. Due attention should be given to this area during retrofitting of existing buildings.

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